Mechanical heat exchanging apparatus

ABSTRACT

Apparatus for cooling a stream of gas having a temperature of about 2,000* F. by mechanical means. An endless metal curtain of simple construction moves at relatively high speed over and between pulley means transverse of the gas stream, and extends into a cooling enclosure. Stretching means are provided to keep the metal curtain under substantially constant tension at any possible temperature encountered, and purging means are provided to insure that the metal curtain is cleaned without contaminating the coolant. I prefer that the pulley means be driven by a variable speed power means which is controlled by a temperature sensing device positioned in the gas downstream so that the gas stream from the apparatus is cooled to a substantially constant temperature.

1451 Mar. 28, 1972 [54] MECHANICAL HEAT EXCHANGING APPARATUS [72]Inventor: Robert G. Ballinger, 604 Browns Lane,

Ross Township, Allegheny County, Pa. 15237 [58] Field of Search ..165/5,6, 10, 7, 60; 55/354;

[56] v References Cited UNITED STATES PATENTS 3,211,213 10/1963 Baxleyet a1. ..l65/9 2,866,624 12/1958 Holmquist 1 65/6 489,651 1/1893Karlsteen ..107/57 866,115 9/1907 Dock ..261/80 1,818,391 8/1931 Greene..261/80X 1,832,374 11/1931 Forby et al ..107/57 X 2,836,398 5/1958Linderoth ..165/5 FOREIGN PATENTS 0R APPLICATIONS 89,244 8/1922 Austria165/6 1,062,263 7/1959 Germany .165/6 1,124,528 3/1962 Germany 165/6693,048 6/ 1953 Great Britain... .165/6 554,507 1/1957 ltaly ...165/6251,895 5/1926 Great Britain 165/6 Primary Examiner-Albert W. Davis, Jr.Attorney-Buell, Blenko & Ziesenheim [57] ABSTRACT Apparatus for coolinga stream of gas having a temperature of about 2,000 F by mechanicalmeans. An endless metal curtain of simple construction moves atrelatively high speed over and between pulley means transverse of thegas stream, and extends into a cooling enclosure. Stretching means areprovided to keep the metal curtain under substantially constant tensionat any possible temperature encountered, and purging means are providedto insure that the metal curtain is cleaned without contaminating thecoolant. I prefer that the pulley means be driven by a variable speedpower means which is controlled by a temperature sensing devicepositioned in the gas downstream so that the gas stream from theapparatus is cooled to a substantially constant temperature.

2 Claims, 6 Drawing Figures PATENTEnmzs 1922 SHEET 1 OF 3 PATENTEnmzsI972 3,651,862

SHEET 2 UF 3 INVENTOR Robert G. Ballinger PATENTEBMAR28 I972 SHEET 3 [1F3 A .m F

INVENTOR Robert G. Bollinger MECHANICAL HEAT EXCHANGING APPARATUS Thisapplication is a continuation-in-part of patent application, Ser. No.782,130, filed December 9, 1968.

This invention relates to a mechanical heat exchanging apparatus used tocool a stream of gas. It is particularly useful for efficiently coolinga gas stream of very high temperature to a substantially constanttemperature without contaminating the coolant.

The use of apparatus to cool a stream of fluid mechanically is broadlyold and well known. It provides a compact and relatively inexpensivemeans of cooling fluid streams such as gases encountered in industrialplants. Such apparatus usually consisted of continuously moving panelsof screen-like material sequentially through a hot gas stream and a coldgas or liquid stream. For example, a wheel having continuousradial-shaped sections of screen-like material was positioned transverseof a hot gas stream and a cold gas stream so that for each revolution,each radial shaped section passed successively through the hot gasstream and the cold gas stream. Or, a belt of spring wire moved over andbetween two pulleys positioned transverse of a hot gas stream and a coldgas stream so that for each revolution of the belt,'a given pointthereon passed successively through the hot gas stream and the cold gasstream. Such mechanical heat exchangers were contemplated for use incooling a fluid stream with a temperature of about 300 F. They wereimpractical for cooling a fluid stream of very high temperature, such asencountered in certain exhaust systems, because the panel of screen-likematerial (i) would bind or slip on the pulley means, (ii) would distortuntil it was incapable of allowing the passage of the gas stream, and/or(iii) could not be moved at high speed.

Mechanical apparatus were not heretofore used to cool gases of such hightemperature. To cool such gases one of three methods were ordinarilyused: (i) mixing the high temperature gas with ambient air; (ii)conducting the gas through an extended system of metal ducts which aresurrounded by ambient air or other coolant, or (iii) conducting the gasthrough a cold water. or other coolant spray. Each of these methods hasone or more disadvantages which made its commercial use undesirable: (i)mixing the gas with ambient air resulted in. uncontrolled temperaturesunder certain atmospheric conditions in the downstream gas, and resultedin larger volumes of gas to filter; (ii) conducting the gas throughextended metal ducts resulted in uncontrolled temperatures in thedownstream gas, and involved large expenditures in fabrication andinstallation of metal ducts; (iii) spraying with water and the likeproduced large amounts of contaminated liquid which in turn presentedproblems in disposal to avoid pollution, and problems in maintenance ofthe equipment because of corrosion and condensation.

The present invention overcomes these disadvantages and difficulties andmakes the use of mechanical heat exchanging apparatus commerciallyfeasible in cooling a high temperature gas stream.

I provide an apparatus for cooling a gas stream of high temperature. Anendless metal curtain is positioned transverse a gas stream and isextended into a cooling enclosure. Pulley means are providedsubstantially out of the gas stream, inside or outside the coolingenclosure, so that they are capable of continuously and sequentiallymoving said metal curtain transverse of said gas stream and through thecooling enclosure. A stretching means is provided to keep the metalcurtain under substantially constant tension as it travels between thepulley means at any possible temperature which may be encountered. Andcooling means are provided in the cooling enclosure to transfer the heatfrom said metal curtain to a coolant.

The metal curtain is made of a material which is stable and inert athigh temperatures and with high fluctuations in temperature. I preferthat the metal curtain be made of a high chromium-nickel alloy steelsuch as Inconel, Incoloy" or stainless. I prefer that the metal curtainbe made of round or flat, preferably thin wire of simple construction,such as chainlink fence construction, which will flex but not bend themetal or wear the joints substantially Stretching means 7 are comprisedof a movable frame 10 and a movable pulley housing 11, which supportpulley means 6 positioned below the cooling enclosure 4. Movable whenthe curtain is moved by the pulley means at relatively high speed. Iprefer that the wire size be in the range of from 0.01 inch to 0.25 inchin diameter, but larger diameter wire can be used, particularly whenused in a laminate as hereinafter described. In this way, the metalcurtain can have an extremely large surface area per unit volume, andyet have a relatively open mesh and in addition tend not to collectcontaminates in the gas stream.

The metal curtain need not be made of a highly efficient heat transfermaterial because of the high temperatures of the gas stream, high speedat which the metal curtain is moved, and the large area per unit volumeexposed to the gas stream. Indeed, I have calculated that a steel wire0.125 inch in diameter can be heated from 200 to l,300 F in 4 secondswhen exposed to an air stream of 1,800" F. If additional mass of metalcurtain is necessary, heavier wire can be used or, preferably theendless metal curtain can be made of multi-layers of wire. In thisconnection, I prefer that endless metal curtain be made of multi-layersof wire with larger diameter, larger mesh wire as a base layer so thatthe useful life of endless metal curtain can be increased withouteffecting its heat transfer efficiency.

The cooling means for transferring heat from the metal curtain to acoolant may be of any suitable kind. For example, it may consist of afan or fans which force a stream of cool gas, such as ambient air,through the cooling enclosure. Or it may consist of nozzles that spraywater (or other suitable liquid which will not evaporate during thecooling operation) over the metal curtain as it passes through thecooling enclosure. ln either case, the heated uncontaminated coolantcould be used to heat a building'or the like.

I prefer that a purge means is provided between the gas stream and thecooling enclosure to clean the metal curtain of any contaminates andthereby insure that the coolant is not contaminated. Such a purge meanscould be simply a rotary brush placed in contact with the metal curtain.But I prefer that the purge means consist of a high velocity stream ofambient air which is jetted through the metal curtain and into the gasupstream of the metal curtain. l contemplate that the gas stream will beunder a negative pressure so that the high velocity stream of ambientair, containing the small amount of contaminates removed from the metalcurtain, will be sucked into the gas stream and ultimately to afiltering system. In this way, the metal curtain is cleaned of the smallamount of contaminates collected and the coolant safe guarded againstcontamination.

I further contemplated that my invention can cool gases moving at highvelocity, e.g., between 2,000 to 3,000 feet per minute, with a gascoolant moving at the same high velocity. I also contemplated that myinvention can be positioned at various orientation relative to gravityand still operate efficiently.

I contemplate that my inventioncan be used to reduce the temperature ofexhaust gases of high temperature such as those coming from electric andopen hearth furnaces and converters used in the reduction of metals.Such exhaust gases usually contain dust, dirt, oxides and/or variousother contaminating material from reduction of scrap, pig iron and thelike, and must be cleaned to avoid pollution before the exhaust gasesare emitted to the open air. Such exhaust gases, however, leave anelectric furnace at a temperature in the range of from 1,500 to 3,000 F.and must therefore be cooled before they can be cleaned. Such exhaustgases have heretofore been cleaned by bag collectors, scrubbers andcyclone separators which require a substantially constant temperaturefor efiicient operation. As explained hereinbefore, the necessarycooling apparatus heretofore available was expensive to fabricate andoperate, and/or resulted in expensive and inefiicient cleaning of suchexhaust gases.

My heat exchanging apparatus will cool such exhaust gases to asubstantially constant temperature at which the cleaning apparatus canbe operated efficiently without capturing contaminates entrained in thegas stream and in turn contaminating a coolant.

I prefer that the pulley means be driven by a variable speed power meansand that the power means be controlled by a temperature sensing devicepositioned in the gas downstream of the metal curtain. By thisarrangement, the gas stream can be cooled to a substantially constanttemperature by my in vention.

Other details, objects and advantages of my present invention becomeapparent as the following description of the presently preferredembodiments thereof proceeds.

In the accompanying drawings I illustrate presently preferredembodiments of my invention in which:

FIG. 1 is a cross-sectional side view of an apparatus for cooling a gasstream of high temperature;

FIG. 2 is an end view of an apparatus for cooling a gas stream of hightemperature taken along the line lI-II of FIG.

FIG. 3 is a partial side view with portions broken away of analternative apparatus for cooling a gas stream of hightemperature;

FIG. 4 is a partial transverse view of an alternative apparatus forcooling a gas stream of high temperature taken along the line IVIV ofFIG. 3;

FIG. 5 is an enlarged perspective view of an alternative endless metalcurtain for apparatus for cooling a gas stream of high temperature asshown in FIG. I and FIG. 3; and

FIG. 6 is an enlarged perspective view of a second altemative endlessmetal curtain for apparatus for cooling a gas stream of high temperatureas shown in FIG. 1 and FIG. 3.

Referring specifically to the drawings, an apparatus for cooling a gasstream of high temperature is comprised of an endless metal curtain 2positioned transverse of a gas stream 3 within a conduit means 5 andtransverse of a cooling enclosure 4. Pulley means 6, is provided abovethe conduit means 5, and pulley means 6 is provided below the coolingenclosure 4. Such pulley means 6, and 6, are capable of continuously andsequentially moving said endless metal curtain 2 transverse of the saidgas stream 3 and transverse of the cooling enclosure 4. A stretchingmeans 7 is provided to keep the metal curtain 2 under substantiallyconstant tension as it travels between the pulley means 6, and 6,, atany possible temperature which may be encountered. And cooling means 8are provided in the cooling enclosure 4 to transfer the heat from theendless metal curtain 2 to a coolant 9.

The endless metal curtain 2 is made of relatively open mesh round wire2a of very simple construction of patterns (as shown in FIG. 5) so thatit can flex easily and yet not bend the wire or wear substantially thejoints 32 of the wire 2a when the metal curtain 2 is driven at speeds ofabout 50 feet/min. The endless metal curtain can be guided by anysuitable means, but preferably flange means 34 (shown on FIG. 3 and FIG.4) are provided toguide the endless metal curtain 2 or 2'.

In alternative embodiments, the endless metal curtain 2 can be of openmesh flat wire 2b (as shown in FIG. 6) with the largest flat surfaces 33of the wire 2b substantially in the direction of the stream of gas; inaddition, the endless metal curtain 2, whether of round wire 2a of flatwire 2b, can be made of multi-layers (as shown in FIG. 5) where thelayer 28 forming the base layer has a larger diameter and mesh than thediameter-and mesh of the wire 29 as an over layer. The endless metalcurtain 2 need not have a high specific heat to be efficient because ofthe high temperatures of the gas stream 3, the high surface area perunit volume of the metal curtain 2, and the high speed of the metalcurtain 2. It is made, however, of high chromium-nickel alloy steel,such as Inconel," Incoloy or stainless, which is able to withstandtemperatures of about I ,500 F. or about 2,500 F. (depending on theapplication) and high fluctuations in temperature, and yet remain inertand stable.

The making of the metal curtain 2 in a plurality of layers greatlyincreases the efficiency of the apparatus. The use of a plurality oflayers allows the introduction of heat transfer mass into the gas stream3 without appreciable increase in the time required to heat the mass.And additional layers can be added without impeding the flexibility ofthe apparatus because the overlayers can be loosely attached to the baselayer without interfering with the operation of the self-adjustingstretching means 7 for keeping substantially constant tension on saidmetal curtain 2. The use of plural layers of metal curtain 2 also canincrease the heat transfer mass without appreciable increase in pressuredrop in gas stream 3 across the metal curtain 2, and without appreciableincrease in the pick-up of dirt and the like or decreasing theremovability of dirt and the like. The cleanability, heat transfer, andpressure drop can be optimized by varying the number of layers of metalcurtain 2, the speed of the metal curtain 2, the cross section area andmesh of wire used for various layers of the metal curtain 2 so that thebest combination will be present in the particular application.

The cooling means 8 is comprised of simply passing a stream of coolant9,, (e.g.,,cold ambient air) through the cooling enclosure 4 and throughthe metal curtain 2. Alternatively and Supplementally, the cooling meansmay have noule means 18 which spray coolant 9, (e.g., cold water) ontothe metal curtain 2 as it passes through the cooling enclosure 4. Thenozzle means 18 should be positioned on the outside of the metal curtain2 on the downstream side so that the water spray contacts the metalcurtain as it enters the cooling enclosure 4 and the coolant 9, willtend not to become entrained in the coolant 9,. In addition, bypositioning the nozzle means 18 outside of the metal curtain 2 there isless chance that the coolant 9, will become contaminated by removingcontaminates from the metal curtain 2. The coolant 9 is collected inmovable pulley housing 11 which acts as a sump, and drain means 19 isprovided to remove the cold water coolant 9, from the movable pulleyhousing 11. pulley housing 11 is dimensioned so that it telescopes overmetal curtain housing 12 and is provided with a seal of asbestos or thelike to form an insulated sliding joint. Movable pulley housing 11 hasfixed flange portions 13, and metal curtain housing 12 has fixed flangeportions 14, each rigidly fastened to its respective housing 11 or 12. Aguided adjustable spring assembly 15, is provided between flangeportions 13 and 14, and is maintained under compression so that themetal curtain 2 is constantly under substantially the same tension atany temperature which may be encountered. In addition, bearing means 27of pulley means 6 is adjustable so that the metal curtain 2 can bealigned for movement on pulley means 6, and 6,. As an added feature asafety stop 26 is provided on adjustable spring assembly 15; by thisarrangement, each safety stop 26 will stop the movable pulley housing 11from coming apart from the metal curtain housing 12 if the metal curtain2 should break.

In an alternative embodiment shown in FIG. 3 and FIG. 4, stretchingmeans 7 are comprised of a movable frame 10' and a movable pulleyhousing 11', which support pulley means 6, positioned below the coolingenclosure 4. Movable pulley housing 11' is dimensioned so that ittelescopes over metal curtain housing 12 and is provided with a seal ofasbestos or the like to form an insulated sliding joint. Movable pulleyhousing 11 has fixed flange portions 13', and metal curtain housing 12has fixed flange portions 14, each rigidly fastened to its respectivehousing 11 or 12'. Adjustable pneumatic cylinders 30 are providedbetween flange portions 13 and 14' and are maintained in compression.Adjustable spring assemblies 31 are fastened between flange portions 13'and 14 and are maintained under tension to support the movable pulleyhousing 11'. In this way, the metal curtain 2 is constantly undersubstantially the same tension at any temperature which may beencountered, but need not support any substantial portions of the weightof the movable pulley housing 11' whether in operation or not inoperation. Supplementally or in the alternative an idler pulley orpulleys (not shown) can also be used in the stretching means 7 to keepsubstantially constant tension on the metal curtain 2.

The metal curtain 2 is driven by pulley means 6,, positioned below thecooling enclosure 4, which in turn is driven by power means 16. Thepower means 16 is rigidly fastened to the movable pulley housing 11.Preferably the power means 16 may be a variable speed motor as shown inFIG. 2 or a variable speed gear drive as shown in FIG. 4. By thisarrangement, the gas stream 3 can be cooled to a substantially constanttemperature by controlling the power means 16 by a temperature sensingdevice 41. Temperature sensing device 41 has portion 42 positioned inthe gas stream 3 downstream of the metal curtain 2 and is electricallyconnected to power means 16 by lead 43.

In addition, a purge means 20 is provided between the conduit means 5and the cooling enclosure 4 to clean the metal curtain 2 so that thecoolants 9, and 9, are not contaminated with contaminates from the gasstream 3 which may collect on the metal curtain 2. The purge means 20 iscomprised of a centrifugal blower 21 which jets a high velocity streamof ambient air through a purge conduit 22 within the metal curtain 2,through the metal curtain 2 and into the gas stream 3, so that the smallamount of contaminates collected on the metal curtain 2 are returned tothe gas stream 3. The gas stream 3 is normally under a negative pressureso that highly efficient seals are not needed to keep the contaminatesfrom finding their way into the cooling enclosure 4.

The metal curtain housing 12 will in some cases have to be made of hightemperature alloy steel or provided with a water jacket because of thehigh temperature of gas stream 3. In other applications, the metalcurtain housing 12, like the movable pulley housing 11, can be made ofordinary low carbon steel because it is surrounded by ambient air whichwill keep it cool. Pulley means 6, will also have to be made of hightemperature alloy steel because of the temperature of the gas stream 3.But in some cases, pulley means 6, like pulley means 6 may be made ofordinary low carbon steel because it is positioned to be cooled. Incertain applications, pulley means 6, is cooled by providing a coolingconduit 23 in the metal curtain housing 11 above the pulley means 6, andpositioning a baffle 24 between said pulley means 6, and the gas stream3 within the metal curtain 2; by this arrangement ambient air is suckedinto the gas stream 3 through the cooling conduit 23 around the battle24 to cool the pulley means 6,.

For easy installation assembly flanges 25 are provided on the metalcurtain housing 12 so that the apparatus can be spotwelded or bolted tostandard metal ducts of a square or rectangular shape.

While I have shown and described certain present preferred embodimentsof my invention, it is to be distinctly understood that the invention isnot limited thereto but may be otherwise variously embodied within thescope of the following claims.

I claim:

1. Apparatus for cooling a gas stream of high temperature comprising: anopen mesh endless metal curtain for receiving heat from said gas streampositioned substantially transverse to said gas stream and extendinginto a cooling enclosure, said endless curtain being comprised of aplurality of layers of wire, pulley means for continuously andsequentially moving said metal curtain substantially transverse of saidgas stream and into the cooling enclosure and positioned substantiallyout of said gas stream, self-adjusting stretching means for keepingsubstantially constant tension on said metal curtain where said metalcurtain is subject to said gas stream of high temperatures such as inthe range of 1,500 to 3,000 F positioned substantially out of said gasstream, and cooling means for transferring heat from said metal curtainto a coolant.

2. Apparatus for cooling a gas stream of high temperature as claimed inclaim 4 wherein: said layer of endless metal curtain forming a baselayer has wire of larger cross-section than the cross-section of thewire of a layer of endless metal curtain positioned over said baselayer.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,651,862 I Dated March 28, 1972 l f Robert G. Ballinger It is certifiedthat error appears in the above-identified patentand that said LettersPatent are hereby corrected as shown below:

Column 2, lines 1, 2 and 3, delete "Stretching means 7 are comprised ofa movable frame 10 and a movable pulley housing 11, which support pulleymeans 6 positioned below the cooling enclosure 1. Movable";

7 Column 1, line 32, after '11." insert Stretching means 7 are comprisedof a movable frame 10 and a movable pulley housing 11, which supportpulley means 6 positioned below the cooling enclosure 4. Movable Signedand sealed this 7th day of November 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents OFlM PO-105O (1069) USCOMM-DC GQB'IB-PBQ U.S, GOVERNMENTPRINTING OFFICE I969 0-356-334,

1. Apparatus for cooling a gas stream of high temperature comprising: anopen mesh endless metal curtain for receiving heat from said gas streampositioned substantially transverse to said gas stream and extendinginto a cooling enclosure, said endless curtain being comprised of aplurality of layers of wire, pulley means for continuously andsequentially moving said metal curtain substantially transverse of saidgas stream and into the cooling enclosure and positioned substantiallyout of said gas stream, self-adjusting stretching means for keepingsubstantially constant tension on said metal curtain where said metalcurtain is subject to said gas stream of high temperatures such as inthe range of 1,500* to 3,000* F., positioned substantially out of saidgas stream, and cooling means for transferring heat from said metalcurtain to a coolant.
 2. Apparatus for cooling a gas stream of hightemperature as claimed in claim 4 wherein: said layer of endless metalcurtain forming a base layer has wire of larger cross-section than thecross-section of the wire of a layer of endless metal curtain positionedover said base layer.